Hydraulic pumps



July 29,1958

Filed Feb. 5. 1954 Fig.7

J. L. GRATZMULLER HYDRAULIC PUMPS 3 Sheets-Sheet 1 y 1958 J. 1.. GRATZMULLER 2,84

HYDRAULIC PUMPS s Sheets-Sheet 2 v Filed Feb. 3. 1954 I ll l1 um Inventor w W W M r W Afl'orneys y 1958 J. L. GRATZMULLER 2,845,029

HYDRAULIC PUMPS Filed Feb. 3. 1954 3 Sheets-Sheet 3 75 I. 73 r. 5 59 I v Invgnfor b flwww kW Attorn y 3 United States Patent 9 HYDRAULIC PUMPS Jean Louis Gratzmuller, Paris, France Application February 3, 1954, Serial No. 408,006

Claims priority, application France February 5, 1953 3 Claims. (Cl. 103-40) through automatic non-return valves of the type in which the movable member of the valve is displaceable solely by the circulation of fluid.

A further object of the invention is to so locate the intake and delivery valves as to ensure the evacuation of air which could be trapped in the pump barrel, at each delivery stroke of the pump.

A still further object of the invention is to locate the delivery and the intake valves coaxially with the pump cylinder one above the other, both valves opening by vertical displacement of the valve movable member by raising from its seat.

Another object of the invention is to provide a complete separation between the pump cylinder, on one side, and the crank-case, on the other side, to avoid suction of the air from the crank-case towards the pump working chamber, as Well as leakage from said working chamber towards said crank-case.

A more particular object of my invention is to form the pump barrel by an elongated metallic element provided with a bore and to stack in said bore, one over the.

other, a plurality of elements having an externally cylindrical shape of a diameter corresponding to the diameter of said bore, said elements constituting the cylinder of the pump, the intake valve, the delivery valve and, finally, a plug provided with the outlet port, said plug being screwed in the upper open end of said bore to keep in place the other three elements.

It is a still more particular object of my invention to make said barrel and said elements, to be stacked inside said barrel, of metals having substantially the same coefficient of thermal expansion, so as to avoid distortions of parts or packing elements interposed between said parts and, hence, leakages under varying temperature conditions.

Another object of my invention is to use as automatic valves and more particularly as the intake valve, valves as described in the co-pending application Ser. No. 406,262, filed on January 26, 1954, by applicant for Non-Return Ball Valve for Reciprocating Hydraulic Pumps.

A further object of my invention is to combine with the pump proper an automatic regulating device.

A still further object of the invention is to use the same metallic body for said pump and said regulating device by providing two parallel bores in said body secured on the crank-case, said two bores receiving, each, a plu- "ice rality of stacked elements kept in place by means of appropriate plugs, said two bores further communicating through holes drilled through said common body and establishing the necessary communications between said two bores.

Other objects and advantages of the invention will be apparent from the following detailed description together with the accompanying drawings, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to subjoined claims.

In these drawings:

Fig. 1 is a sectional view of a hydraulic pump according to the invention;

Fig. la is a detail vertical section taken on the line 1a-1a of Fig. 1;

Fig. 2 is a partly elevational and partly cross-sectional view along the axis XX of Fig. 1;

Fig. 3 is a partly axial sectional view showing an alternative embodiment of the pump barrel, and

Fig. 4 is an axial sectional view showing a portion of the pump of Fig. 1, combined with a sucking rate regulator.

Referring to the drawings and more particularly to Figs. 1 and 2, there are shown at 1 the crank-case and at 2 the barrel of the pump screwed in the top wall 20 of said crank-case.

Inside the barrel 2 are stacked: a member 3 constituting the cylinder of the pump, a member 4 provided with an inlet passage, a member 5 provided with an outlet passage and a plug member 6, which, in the example shown, is screwed in the threaded end of barrel 2 and holds in place the whole assembly of the above described members, suitable packing rings such as 7, 8 and 9 being interposed between the relevant members of the stack.

It is to be noted that the packing rings 8 and 9 ensure tightness both between members 3 and 4 and members 5 and 6, respectively, and between said members and the inner wall of barrel 2. Members 3, 4, 5 and 6 are made of a metal having the same coeificient of thermal expansion as barrel 2, so as to avoid any leakage or destruction of the packing rings, as the temperature of the pump varies in operation. Preferably, the pump barrel 2 as well as parts 3, 4, 5 and 6 are made of ferrous metal.

It will be understood that this mode of assembling the various members of the pump by merely stacking them permits a rapid and easy assembling and dismantling of the pump. 10a is the inlet of the pump to which the liquid is fed through a suitable pipe, 10b. 11 is the outlet provided through plug 6. The intake valve which, in the example shown, is of the type described in the above cited patent application, essentially comprises a ball 51 cooperating with a seat 12 and guided and centered by a tubular extension 13 of member 4. The liquid is sucked into the pump through inlet 10a, a passage 14 and lateral holes 16 drilled through the wall of the tubular extension 13 in the near vicinity of seat 12.

The delivery valve which is formed in member 5 comprises a ball 17 cooperating with a seat 18. This last valve, of a more conventional type, ofiers between ball 17 and its cylindrical housing, suflicient annular clearance to permit flowing of the liquid towards outlet 11. Both valves are provided with abutment means to limit the lifting stroke of their respective ball, said abutment means being each constituted by a gudgeon pin 19.

It is obvious that both valves may be of the type described in the above cited application, if preferred.

It is to be noted that the delivery valve is located directly above the intake valve, said valves being both so designed that the air which could be accumulated in the pump cylinder before the pump is started will tend naturally to escape through outlet 11.

As mentioned above, according to the invention, a complete separation is provided between barrel 2 and crank-case 1, said separation being ensured by an annular space formed between the plunger piston 21 and cylinder 3, said space freely communicating with the liquid tank, as shown in Fig. 1.

In the example shown in Fig. 1, the annular space 52 is formed by a portion 22 of reduced diameter of piston 21, said portion extending over an axial length of the piston 21 at least equal to the stroke of said piston, so as to establish a permanent communication through at least one passage 24 with an annular chamber 23 constantly communicating in turn through a fitting 25 and an individual pipe 58 with the tank 57 (as in Fig. 4).

' The long piston part extending between the pump chamber and the portion 22 of reduced diameter already ensures a good tightness. However, leakages can still occur, particularly when the pump delivers liquid under a very high pressure.

It will be readily understood that these leakages will return to the liquid tank through the free communication offered by pipe 58 rather than forcing their way between the lower part of the piston and cylinder towards the crank-case 1.

Another important advantage of maintaining the annular space 52in permanent and free communication with the tank 57 is to ensure in said space a constant liquid pressure slightly superior to the pressure in the crankcase 1. Due to this liquid pressure seal, air cannot be sucked into the pump chamber during the suction stroke.

Still another advantage of the complete separation between barrel 2 and crank-case 1 is that of permitting the use in the latter of any desired lubricant, whatever the nature of the liquid delivered by the pumping unit. As shown in Fig. 3, it is possible, in certain cases, to suppress the special independent duct 58 and to establish a permanent communication between the annular chamber 23 and, hence, the annular space 52 and a space upstream the intake valve, the inlet port 14 of which is at the same pressure as the feeding tank, by means of passages 26. This simplified arrangement may be adopted, in particular, when the feeding tank is located in the near vicinity of the pump, so that no objectionable loss of pressure is to be feared.

On the contrary, when such losses of pressure could happen in the main feeding pipe 101), e. g. in the case when the feeding tank is located at a considerable distance from the pump, it will be preferred to adopt the embodiment described with reference to Figs. 1 to 3 in which the presence of the independent duct 58 through which no forced circulation of liquid takes place maintains with safety in the annular space 52 the slight above mentioned over-pressure.

It goes without saying that it is possible, Within the scope of the invention, instead of providing a portion of reduced diameter in the piston, to provide a portion of enlarged diameter in the cylinder along a suitable axial length to obtain an annular space similar to 52, both dispositions being combined if required.

Referring again to Figs. 1 and 2, piston 21 is reciprocated by means of a disc-shaped member 27 freely pivoted around an eccentric crank-pin portion 28 of a shaft, the same being generally indicated at A.

Shaft A is journalled into cylindrical bearing surfaces 29 and 30 of different diameters directly bored in two opposed walls of crank-case I.

Said crank-case is preferably made of a metal having a high coefficient of thermal expansion and a low modulus of elasticity such as aluminium. Due to this arrangement, it is possible to journal a steel shaft A directly in the above described bearing portions bored in crankcase 1 without any risk of jamming.

Thus, a certain flexibility of the crank-case walls and the high coefficient of thermal expansion of the metal of said walls ensure a good operation of the pump without providing any special bearings to journal shaft A.

The connection between piston 21 and the eccentric 27 is shown as constituting a universal joint. The end of piston 21 is engaged in slot of a pivot pin 31 freely rotatable in a cylindrical housing 32 of the eccentric 27, the connection between pivot pin 31 and piston 21 being ensured by a cylindrical gudgeon pin 33.

The assembling of the various members of the mechanical driving connection is made easier by the hereunder described constructive arrangement. A passage 34 is provided through the eccentric 27, so that it suffices to bring the cylindrical holes provided in pivot pin 31 by an angular displacement around the axis of the cylindrical housing 32 into registration with said passage 34 after having introduced the end of piston 21 into its slot in said pin 31, whereupon the cylindrical gudgeon pin 33 may be easily passed through its three cylindrical housings provided in the end of piston 21 and in pivot pin 31 on either side of said piston end.

Once the piston is brought back into its normal position, the cylindrical gudgeon pin 33 finds itself automatically secured against escape. This universal joint feature permits avoiding the difiiculties of providing accuracy in the relative positioning of piston 21 with respect to shaft A. As already mentioned above, the journalled portions 29 and 30 of shaft A have different diameters, while shaft A proper offers an end 35 of reduced diameter adapted to be journalled in bearing surface 29, a crank-pin portion 8 of greater diameter and, finally, a portion 36 of still greater diameter adapted to be journalled in the bearing surface 30 of the crankcase 1.

This arrangement permits mounting the shaft by introducing the same with its reduced end 35 ahead, first into the bearing surface 30, then into the eccentric 27 and, finally, into the bearing surface 29. Once shaft A is mounted as just described, it. is secured by means of a plug 38 provided with a hole through which passes the end 37 of shaft A on which a suitable driving member, such as a pulley 39, is keyed.

The lubrication of shaft A is ensured by rings such as 40 freely suspended on shaft A and held in a depending position, e. g. by a piano wire 41 held in turn by studs 124. Inclined passages 42 and 43 ensure the circulation of the lubricating oil in the bearing portions in which shaft A is journalled.

In order to avoid leakages of lubricating oil at the driven end of the shaft, there is formed on said shaft end a frusto-conical portion 44, while an annular groove with a rounded cross-section 45 is provided in plug 38. The frustro-conical portion 44 of the shaft and said fixed groove 45, in which the edge of portion 44 slightly penetrates, ensure projection of the leaking oil when shaft A is rotated into groove 45 from which said oil flows through the inclined passage 43 into the pump crank-case 113.

In Fig. 4 is shown a pump combined with a feeding rate regulator mounted in the pump barrel 2, in a second cylindrical bore parallel to that containing the pump and communicating at its lower end (in the drawing) with the feeding duct 59 from the supply tank 57, through a radial passage 63 with the inlet 10, and through another radial passage 64 with the delivery port 65 of the pump, located downstream the delivery valve 17 and leading to outlet 11.

In the regulator cylindrical bore, there are mounted by a mere stacking:

. A valve body 66, provided with an axial passage 67 formed with a seat 68 for a valve movable member which is constituted by a ball 69, the lifting of which is controlled by a plunger piston 70,

A cylinder member 71, in which said piston is slidably mounted, and which is provided with oblique ports 72 leading to an annular groove and establishing a communication between the feeding duct 59, through the axial passage 67 controlled by the ball 69, and the radial port 63 and, hence, the inlet 10,

The regulator body proper 73, communicating through a radial bore 78 and an axial groove 77 with port 65 and, hence, with the outlet 11 and, finally, to hold the whole assembly against a shouldering adjacent the bottom of the bore,

A threaded plug 74 which is screwed in the upper threaded end of said bore.

The tightness of the regulation chamber is ensured by washers 75 and 75a, the latter ensuring concurrently with a third washer 76' the tightness of the controlled communication between the feeding duct and the pump inlet 10. The regulation chamber encloses a disc 79 mounted with a substantial clearance in said chamber on the upper end of a rod 80, the lower end of which is guided with clearance in a sleeve 81 fast with the cylinder member 71 in which the above-mentioned piston 70 is slidably mounted. Piston 70 is mounted on the rod 80 through the intermediary of a kind of universal joint, as shown at 82. Grooves 83 axially spaced along the whole length of piston 70 are provided to reduce the friction between said piston and its cylinder. Finally, springs 84 and 84a are interposed between disc 79 and the bottom of the regulation chamber. 86, 87 and 88 are threaded plugs tightly closing, by the interposition of packing washers 86a, 87a, 88a, the hole through which the members stacked in the bore of the common body 2 are to be extracted for dismantling, as well as the drilling holes through which the radial ports 63 and 64 have been machined.

This device operates as follows:

The utilization pressure in the regulation chamber exerts on piston 70 a thrust tending to apply ball 69 on its seat 68.

Springs 84 are so calibrated as to compensate said thrust for a predetermined value of the utilization pressure. Below this value, springs 84 drive piston 70 upwardly, thus, permitting a more or less substantial lifting of ball 69. Conversely, upon an increase in pressure over the above mentioned predetermined value of the utilization pressure, ball 69 is applied on its seat. In these conditions, when the output pressure of the pump becomes excessive, the cross-section of passage 67 controlled by ball 69 is reduced, and thus limits or even completely suppresses, if necessary, the feeding rate into inlet and therefore the rate of discharge of the pump. In spite of the negative pressure which is thus created at the pump inlet, said pump cannot be unprimed due to the fact that the annular groove 52 is permanently filled with oil under a slight over-pressure, as explained above.

What is claimed is: i

1. In a combination with a reciprocating pump coinprising a barrel having a bore accommodating the piston and the inlet and outlet valves of the pump, a second bore in said barrel, a feed-rate regulator mounted in said sec ond bore and including three cylindrical members fitting closely in said bore in stacked relationship, the first of said members having an inlet passage, the second member having an axial bore and a passageway interconnecting said inlet passage of the first member with said inlet valve of the pump, and the third member forming a chamber having a radial port communicating with said outlet valve of the pump whereby the delivery pressure of said pump is communicated to said chamber, a check valve in said inlet passage of the first member, a plunger slidable in said axial bore of the second member and having one end adapted to contact said check valve and its other subjected to said delivery pressure in said chamber, and calibrated spring means in said chamber arranged to urge said plunger away from said check valve, said delivery pressure in said chamber acting in opposition to said spring means to move the plunger so as progressively to limit the opening of said check valve as the pump delivery pressure increases and utimately to close the check valve when said delivery pressure reaches a predetermined value.

2. The combination according to claim 1, in which said chamber is closed by a plug member which secures said three cylindrical members in said stacked relationship.

3. The combination according to claim 1, in which said pump barrel and said three cylindrical members are made of materials having substantially the same coetficient of thermal expansion.

References Cited in the file of this patent UNITED STATES PATENTS 765,026 Mason July 12, 1904 1,685,424 Hurrell Sept. 25, 1928 1,905,284 Heitger Apr. 25, 1933 1,958,948 Knecht May 15, 1934 2,007,871 Oldham July 9, 1935 2,131,749 Ofeldt Oct. 4, 1938 2,131,779 Zwick et al. Get. 4, 1938 2,295,833 Deschamps Sept. 15, 1942 2,433,220 Huber Dec. 23, 1947 2,645,182 Tucker July 14, 1953 2,691,388 Livers Oct. 12, 1954 FOREIGN PATENTS 252,418 Switzerland Dec. 31, 1947 697,008 Germany Oct. 3, 1940 854,864 Germany Nov. 6, 1952 949,264 France Feb. 14, 1949 953,629 France May 23, 1949 962,293 France Dec. 5, 1949 

